Heat exchanger coil assemblies are well known in the art. One such heat exchanger assembly is disclosed in U.S. Pat. No. 6,889,759 to Derosier and illustrated in FIGS. 1-9. In FIG. 1, a heat exchanger 10 includes a finned coil assembly 12, a housing 14 and a blower 16. Arrows 17 indicate a direction of air flow being drawn through the heat exchanger 10 by way of example only. The heat exchanger 10 includes an inlet manifold 18, an outlet manifold 20 and respective inlet and outlet pipes 19 and 21. Tubes 22 are joined by return bends 24. As is well-known in the art, an internal heat exchanger fluid is circulated from an inlet source through the inlet pipe 19 and the inlet manifold 18, then through the finned coil assembly 12, and then through the outlet manifold 20 and the outlet pipe 21 so that heat is exchanged between the internal heat exchange fluid in the coil assembly 12 and air that is drawn through the coil assembly 12 by the blower 16.
As shown in FIG. 1, a plurality of fins 26 constitutes the finned coil assembly 12. FIG. 2 discloses a single fin 26 fabricated from a plate material such as metal with acceptable heat exchange properties and is formed with a continuous series of corrugations 30 as best shown in FIG. 3. Note that the continuous series of corrugations 30 extend horizontally across the plate yet some of the corrugations as they extend horizontally across the plate are interrupted periodically by a plurality of conduit portions 32 arranged in a matrix of columns and rows as shown in FIGS. 2 and 3. With reference to FIG. 3, each conduit portion 32 has a flat piece 34 and collar 36. Each flat piece 34 is generally disposed in an imaginary reference plane RP as shown in FIGS. 3 and 4. Each flat piece 34 has a hole 38 that is formed through the fin 26. A respective collar 36 is connected to and projects from a corresponding one of the flat pieces 34 to define a transversely extending conduit 40 in communication with the hole 38.
With reference to FIG. 5, each corrugation 30 projects from the reference plane RP as viewed in cross-section at a height “h” and criss-crosses the reference plane RF as viewed in cross-section at a width w. A ratio h:w is in a range of approximately 0.32 and 0.7. Also, a number of corrugations 30 per inch as viewed in cross-section is in a range of approximately 8 and 24. Such fin 26 is considered a high-frequency, low-amplitude corrugated fin because this fin 26 includes many corrugations 30 connected in sequence in an exemplary form as a sine wave configuration within a relatively short distance as viewed in cross-section and the height “h” of the corrugations 30 is rather small. In other words, the high-frequency, low-amplitude corrugated fin 26 is a substantially continuous sequences of corrugations 30 occasionally interrupted by the conduit portions. Furthermore, a skilled artisan would comprehend that other cross-sectional configurations might be used such as a saw-toothed cross-sectional configuration, a trapezoidal cross-sectional configuration or other cross-sectional configurations known in the art.
The high-frequency, low-amplitude corrugated fin 26 as illustrated in the drawing figures performs as designed in many heat exchange applications. For instance, the high-frequency, low-amplitude corrugated fin 26 performs as designed when air flowing between facially-opposing fins 26 is to be heated. However, when the air flowing between facially-opposing fins 26 is to be cooled, particularly in a highly humid environment, there is a concern regarding moisture build-up on the high-frequency, low-amplitude corrugated fins 26. In a highly humid environment, if cooling of the air results in a temperature drop below the dew point, moisture can accumulate on the fins 26 resulting in a decrease of heat exchange efficiency. Furthermore, a sufficient amount of moisture can condense and accumulate within the valleys defined by the respective corrugations 30 forming water Wa in the valleys as shown by way of example in FIG. 6 effectively creating a liquid insulation layer between the flowing air and the fins themselves. It is theorized that since the fins 26 are high-frequency, low-amplitude corrugated fins, the curved walls forming the corrugations 30 retain the water in the valleys as a result of the capillary action. A significant amount of water can be retained in the valleys of the corrugations 30 by capillary action resulting in yet a further decrease of heat exchange efficiency of the finned coil assembly 12.
To overcome the problem of water being retained in the valleys of the high-frequency, low-amplitude corrugated fins 26, a modification can be made by orienting the corrugations 30 at an angle inclined relative to horizontal as shown in FIG. 7. Empirical test results indicate the optimum inclined angle might be in a range of 15° and 25° although other angles can be used. Note all of the corrugations 30 extend linearly at an inclined angle “a” relative to a horizontal line HL. As a result, water accumulating in the valleys as a result of capillary action can now drain by flowing downwardly along the inclined corrugations 30 and over the peaks of the corrugations 30 towards the edge of the fin 26 as illustrated by way of example in FIG. 7 by the multiple curving arrows CA.
In some applications, the high-frequency, low-amplitude corrugated fin 26 with its corrugations 30 extending at an inclined angle relative to horizontal is satisfactory. However, in other applications, using this high-frequency, low-amplitude corrugated fin 26 might be unsatisfactory. For example, in the processing plants such as meat processing plants which require refrigeration, government officials might shut down plant operations if water (most likely, in tiny droplet form) is carried outside of the housing 14. This situation might occur if the flowing air blows accumulated water off the outer vertical edges of the fins 26. To overcome this problem, two fins 26a and 26b with corrugations 30 oriented at inclined angles relative to horizontal could be used as the finned coil assembly 12 as shown in FIG. 8. Fin 26a and fin 26b are arranged juxtaposed to one another with the corrugations 30a of fin 26a oriented at an inclined angle relative to horizontal that directs water that might have accumulated in the valleys toward fin 26b and with the corrugations 30b of fin 26b oriented at an inclined angle relative to horizontal that directs water that might have accumulated in the valleys toward fin 26a. With this arrangement of angled corrugations, water flows toward and drains in the center of the heat exchanger 10 indicated by arrow W.
However, arranging two high-frequency, low-amplitude corrugated fins 26a and 26b in this manner has drawbacks. First, it is difficult to abut the two opposing ends of fins 26a and 26b at the center of the heat exchanger 10 in complete registration. As a result, a crack 42 is formed between the fins 26a and 26b. Such crack 42 increases the pressure drop of the air flowing from fin 26a to fin 26b resulting in reduced air flow, which, in turn, results in decreased heat exchange efficiency.
Furthermore, since complete registration of the two opposing ends of the fins 26a and 26b is difficult to achieve, the opposing corrugations 30a and 30b of the respective ones of the fins 26a and 26b might be positioned offset from one another as illustrated by way of example only in FIGS. 9A and 9B. Thus, fin 26b disposed offset from fin 26a effectively introduces structure into the air flow stream causing yet another pressure reduction, which, in turn, results in decreased heat exchange efficiency.
Also, although the juxtaposed fins 26a and 26b arranged as described above, might be a potential solution to draining away water accumulated in the valleys of the corrugations 30, in practice, fins with such angled corrugations are difficult to manufacture. It was noted during the manufacture of such fins with inclined-angled corrugations that the fin tended to move sideways through the forming tooling as it advanced therethrough resulting in the fin moving sideways off of the forming tooling.
It would be advantageous to provide a fin for a heat exchanger coil assembly that provides enhanced drainage for water that accumulates as a result of condensation. It would be preferable to provide a fin that permits water drainage between the opposing vertical edges of the fin and inhibits or minimizes water build-up on either one of the opposing vertical edges of the fin. It would also be advantageous to provide a fin for a heat exchanger coil assembly that drains water in a manner to inhibit water build-up in the valleys of the corrugations. The present invention provides these advantages.